The present invention relates to an image forming apparatus in which an image can be obtained in such a manner that: a toner image is formed on an image carrier by means of electrophotography; and the formed toner image is transferred onto a transfer sheet. The present invention more particularly relates to an image forming apparatus such as a printer, copier and facsimile in which a process cartridge is detachably provided, wherein the image carrier and at least one of a developing means and cleaning means are integrally installed in the process cartridge.
As the size of an image forming apparatus such as a printer and copier has been made small, and its functions have been improved, the structure of the image forming apparatus has become highly precise and complicated.
When the conveyance of a transfer sheet is blocked in its conveyance passage, what is called a jam occurs, and the jammed transfer sheet (which will be referred to as a jammed paper, hereinafter) must be removed from the apparatus. In order to remove the jammed paper, a working space into which an operator can reach, must be made in the apparatus in such a manner that: an external door of the image forming apparatus can be opened; and a portion of a transfer sheet passage or all of the transfer paper passage is moved if necessary. Since the aforementioned work to remove the jammed paper is conducted by an operator who is an untrained user, the structure of the apparatus must be made simple so that the work can be conducted without expertise.
Recently, an image forming apparatus having a process cartridge in which an image carrier and at least one of a developing means and a cleaning means are integrated into one unit, has been developed so that an operator can maintain the apparatus easily.
In the case of an image forming apparatus such as a printer and a copier having a process cartridge, when an image carrier provided in the process cartridge is consumed or deteriorated, the process cartridge itself is replaced with a new one, so that an operator can maintain the image forming apparatus without any expertise. In the apparatus described above, the apparatus is provided with a guide member by which the process cartridge can be guided, and all the operator must do is to insert the process cartridge into the apparatus along the guide member.
In a conventional image forming apparatus, the direction of process cartridge removal and that of transfer sheet movement make a right angle with each other, so that the work of process cartridge removal is troublesome and complicated, and further the space to install the image forming apparatus is restricted. Furthermore, a wide space is required to maintain the apparatus.
In order to solve the aforementioned conventional problems, an image forming apparatus disclosed in the official gazette of the Japanese Patent Publication Open to Public Inspection No. 279870/1986 has been proposed. In the apparatus disclosed in the aforementioned official gazette, the direction of the transfer sheet movement agrees with the direction of process cartridge removal, so that the parts can be easily replaced and the operation can be conducted easily, and further, the working space is not restricted. However, in the case of the image forming apparatus disclosed in the official gazette of the Japanese Patent Publication Open to Public Inspection No. 279870/1986, the process cartridge is replaced in such a manner that: the upper housing of the apparatus is opened, and the operator must pull the process cartridge from the apparatus and then take it out. Therefore, the work is very hard for the operator when the process cartridge is large and heavy.
In the case where a paper jam has occurred in the conveyance passage, the operator must put his hands into a small space in the apparatus in order to remove the jammed paper. Even when the upper housing has been opened, it is difficult for the operator to ensure a sufficiently wide working space, so that it is hard to remove the jammed paper from the transfer sheet conveyance passage. In order to ensure a sufficiently wide working space, the operator must pull the process cartridge out of the upper housing, which is complicated and troublesome. As described above, the aforementioned apparatus has the defect that jam treatment is difficult.